#' Generate TNA-style Color Palette for Nodes

#'

#' Internal function that generates appropriate qualitative colors based on

#' the number of states, following TNA's color palette logic.

#'

#' @param n_states Number of states (nodes) in the network.

#' @return Character vector of colors.

#' @keywords internal

tna_color_palette <- function(n_states) {

  # Check for required packages with fallbacks

    # 1-2 states: Accent palette (first n colors)

    } else {

    },

    # 3-8 states: Full Accent palette

    } else {

    },

    # 9-12 states: Set3 palette

    } else {

    },

    # 13+ states: colorspace qualitative HCL

    } else {

    }

  )

}

#' Convert a tna object to cograph parameters

#'

#' Extracts the transition matrix, labels, and initial state probabilities

#' from a \code{tna} object and plots with cograph. Initial probabilities

#' are mapped to donut fills.

#'

#' @param tna_object A \code{tna} object from \code{tna::tna()}

#' @param engine Which cograph renderer to use: \code{"splot"} or \code{"soplot"}.

#'   Default: \code{"splot"}.

#' @param plot Logical. If TRUE (default), immediately plot using the chosen engine.

#' @param weight_digits Number of decimal places to round edge weights to. Default 2.

#'   Edges that round to zero are removed unless \code{show_zero_edges = TRUE}.

#' @param show_zero_edges Logical. If TRUE, keep edges even if their weight rounds to

#'   zero. Default: FALSE.

#' @param ... Additional parameters passed to the plotting engine (e.g., \code{layout},

#'   \code{node_fill}, \code{donut_color}).

#'

#' @details

#' ## Conversion Process

#' The tna object's transition matrix becomes edge weights, labels become

#' node labels, and initial state probabilities (\code{inits}) are mapped to

#' \code{donut_fill} values to visualize starting state distributions.

#'

#' TNA networks are always treated as directed because transition matrices

#' represent directional state changes.

#'

#' The default \code{donut_inner_ratio} of 0.8 creates thin rings that

#' effectively visualize probability values without obscuring node labels.

#'

#' ## Parameter Mapping

#' The following tna properties are automatically extracted:

#' \itemize{

#'   \item \strong{weights}: Transition matrix \code{->} edge weights

#'   \item \strong{labels}: State labels \code{->} node labels

#'   \item \strong{inits}: Initial probabilities \code{->} donut_fill (0-1 scale)

#' }

#'

#' ## TNA Visual Defaults

#' The following visual defaults are applied for TNA plots (all can be overridden via \code{...}):

#' \itemize{

#'   \item \code{layout = "oval"}: Oval/elliptical node arrangement

#'   \item \code{node_fill}: Colors from TNA palette (Accent/Set3 based on state count)

#'   \item \code{node_size = 7}: Larger nodes for readability

#'   \item \code{arrow_size = 0.61}: Prominent directional arrows

#'   \item \code{edge_color = "#003355"}: Dark blue edges

#'   \item \code{edge_labels = TRUE}: Show transition weights on edges

#'   \item \code{edge_label_size = 0.6}: Readable edge labels

#'   \item \code{edge_label_position = 0.7}: Labels positioned toward target

#'   \item \code{edge_start_style = "dotted"}: Dotted line at edge source

#'   \item \code{edge_start_length = 0.2}: 20% of edge is dotted

#' }

#'

#' @return Invisibly, a named list of cograph parameters that can be passed to

#'   \code{splot()} or \code{soplot()}.

#'

#' @seealso

#' \code{\link{cograph}} for creating networks from scratch,

#' \code{\link{splot}} and \code{\link{soplot}} for plotting engines,

#' \code{\link{from_qgraph}} for qgraph object conversion

#'

#' @examples

#' \dontrun{

#' # Convert and plot a tna object

#' library(tna)

#' trans <- tna(transitions)

#' from_tna(trans)  # Plots with donut rings showing initial probabilities

#'

#' # Use soplot engine instead

#' from_tna(trans, engine = "soplot")

#'

#' # Customize the visualization

#' from_tna(trans, layout = "circle", donut_color = c("steelblue", "gray90"))

#'

#' # Extract parameters without plotting

#' params <- from_tna(trans, plot = FALSE)

#' # Modify and plot manually

#' params$node_fill <- "coral"

#' do.call(splot, params)

#' }

#'

#' @export

from_tna <- function(tna_object, engine = c("splot", "soplot"), plot = TRUE,

                     weight_digits = 2, show_zero_edges = FALSE, ...) {

  }

  # --- Weights matrix ---

  # --- Build params ---

  )

  # --- TNA-specific visual defaults (can be overridden via ...) ---

  # --- Apply overrides ---

  }

  # --- Plot ---

    }

    }

  }

}

#' Convert a qgraph object to cograph parameters

#'

#' Extracts the network, layout, and all relevant arguments from a qgraph

#' object and passes them to a cograph plotting engine. Reads resolved values

#' from \code{graphAttributes} rather than raw \code{Arguments}.

#'

#' @param qgraph_object Return value of \code{qgraph::qgraph()}

#' @param engine Which cograph renderer to use: \code{"splot"} or \code{"soplot"}.

#'   Default: \code{"splot"}.

#' @param plot Logical. If TRUE (default), immediately plot using the chosen engine.

#' @param weight_digits Number of decimal places to round edge weights to. Default 2.

#'   Edges that round to zero are removed unless \code{show_zero_edges = TRUE}.

#' @param show_zero_edges Logical. If TRUE, keep edges even if their weight rounds to

#'   zero. Default: FALSE.

#' @param ... Override any extracted parameter. Use qgraph-style names (e.g.,

#'   \code{minimum}) or cograph names (e.g., \code{threshold}).

#'

#' @details

#' ## Parameter Mapping

#' The following qgraph parameters are automatically extracted and mapped to

#' cograph equivalents:

#'

#' \strong{Node properties:}

#' \itemize{

#'   \item \code{labels}/\code{names} \code{->} \code{labels}

#'   \item \code{color} \code{->} \code{node_fill}

#'   \item \code{width} \code{->} \code{node_size} (scaled by 1.3x)

#'   \item \code{shape} \code{->} \code{node_shape} (mapped to cograph equivalents)

#'   \item \code{border.color} \code{->} \code{node_border_color}

#'   \item \code{border.width} \code{->} \code{node_border_width}

#'   \item \code{label.cex} \code{->} \code{label_size}

#'   \item \code{label.color} \code{->} \code{label_color}

#' }

#'

#' \strong{Edge properties:}

#' \itemize{

#'   \item \code{labels} \code{->} \code{edge_labels}

#'   \item \code{label.cex} \code{->} \code{edge_label_size} (scaled by 0.5x)

#'   \item \code{lty} \code{->} \code{edge_style} (numeric to name conversion)

#'   \item \code{curve} \code{->} \code{curvature}

#'   \item \code{asize} \code{->} \code{arrow_size} (scaled by 0.3x)

#' }

#'

#' \strong{Graph properties:}

#' \itemize{

#'   \item \code{minimum} \code{->} \code{threshold}

#'   \item \code{maximum} \code{->} \code{maximum}

#'   \item \code{groups} \code{->} \code{groups}

#'   \item \code{directed} \code{->} \code{directed}

#'   \item \code{posCol}/\code{negCol} \code{->} \code{edge_positive_color}/\code{edge_negative_color}

#' }

#'

#' \strong{Pie/Donut:}

#' \itemize{

#'   \item \code{pie} values \code{->} \code{donut_fill} with \code{donut_inner_ratio=0.8}

#'   \item \code{pieColor} \code{->} \code{donut_color}

#' }

#'

#' ## Important Notes

#' \itemize{

#'   \item \strong{edge_color and edge_width are NOT extracted} because qgraph bakes

#'     its cut-based fading into these vectors, producing near-invisible edges.

#'     cograph applies its own weight-based styling instead.

#'   \item The \code{cut} parameter is also not passed because it causes faint edges

#'     with hanging labels.

#'   \item Layout coordinates from qgraph are preserved with \code{rescale=FALSE}.

#'   \item If you override layout, rescale is automatically re-enabled.

#' }

#'

#' @return Invisibly, a named list of cograph parameters that can be passed to

#'   \code{splot()} or \code{soplot()}.

#'

#' @seealso

#' \code{\link{cograph}} for creating networks from scratch,

#' \code{\link{splot}} and \code{\link{soplot}} for plotting engines,

#' \code{\link{from_tna}} for tna object conversion

#'

#' @examples

#' \dontrun{

#' # Convert and plot a qgraph object

#' library(qgraph)

#' adj <- matrix(c(0, .5, .3, .5, 0, .4, .3, .4, 0), 3, 3)

#' q <- qgraph(adj)

#' from_qgraph(q)  # Plots with splot

#'

#' # Use soplot engine instead

#' from_qgraph(q, engine = "soplot")

#'

#' # Override extracted parameters

#' from_qgraph(q, node_fill = "steelblue", layout = "circle")

#'

#' # Extract parameters without plotting

#' params <- from_qgraph(q, plot = FALSE)

#' names(params)  # See what was extracted

#'

#' # Works with themed qgraph objects

#' q_themed <- qgraph(adj, theme = "colorblind", posCol = "blue")

#' from_qgraph(q_themed)

#' }

#'

#' @export

from_qgraph <- function(qgraph_object, engine = c("splot", "soplot"), plot = TRUE,

                         weight_digits = 2, show_zero_edges = FALSE, ...) {

  }

  # --- Input matrix ---

    }

  }

  # --- Build params ---

  # Layout: use computed coordinates

  }

  # --- Node aesthetics from graphAttributes$Nodes ---

  # --- Edge colors from qgraph arguments ---

  # --- Pie → Donut mapping ---

  # qgraph pie values are single values per node (e.g. from tna)

  # Use graphAttributes$Nodes$pie which has the resolved values

    } else {

    }

    }

  }

  # --- Reorder per-edge vectors via matrix intermediary ---

  # qgraph's Edgelist order may differ from cograph's which(x!=0, arr.ind=TRUE) order.

  # Place each per-edge vector into an n×n matrix keyed by (from, to), then extract

  # in the order cograph will use.

    }

    } else {

    }

  }

  # --- Edge aesthetics from graphAttributes$Edges ---

  # edge_color and edge_width are intentionally not passed — qgraph bakes its

  # cut-based fading into these vectors, producing near-invisible edges. Let

  # cograph apply its own weight-based styling instead.

  # --- Graph-level from graphAttributes$Graph ---

  # cut is intentionally not passed — qgraph's cut causes faint edges with hanging labels

  # --- Directedness from Edgelist ---

  # --- Apply overrides (user can override anything) ---

  # Map qgraph-style parameter names to cograph equivalents

  }

  # If user overrides layout, remove rescale=FALSE so cograph rescales properly

  }

  # --- Plot ---

    }

    # Filter to only params accepted by the target engine

    }

    # soplot expects scalar edge params; collapse per-edge vectors

        }

      }

    }

  }

}

#' Map qgraph lty codes to cograph edge style names

#' @param lty Numeric or character vector of R line types

#' @return Character vector of cograph style names

#' @keywords internal

map_qgraph_lty <- function(lty) {

}

#' Map qgraph shape names to cograph equivalents

#' @param shapes Character vector of qgraph shape names

#' @return Character vector of cograph shape names

#' @keywords internal

map_qgraph_shape <- function(shapes) {

  )

}

#' @title Aesthetic Scale Functions

#' @description Functions for creating aesthetic scales.

#' @name aes-scales

#' @keywords internal

NULL

#' Create a Size Scale

#'

#' Map values to sizes.

#'

#' @param values Values to map.

#' @param range Output size range.

#' @param trans Transformation: "linear", "sqrt", "log".

#' @return Scaled values.

#' @keywords internal

scale_size <- function(values, range = c(0.03, 0.1), trans = "linear") {

  # Apply transformation

  )

  # Normalize

  }

}

#' Create a Color Scale

#'

#' Map values to colors.

#'

#' @param values Values to map.

#' @param palette Color palette (vector of colors or palette function name).

#' @param limits Optional range limits.

#' @return Character vector of colors.

#' @keywords internal

scale_color <- function(values, palette = "viridis", limits = NULL) {

  # Get colors

    # Palette name

      # Try as a single color

    }

  } else {

  }

}

#' Create a Categorical Color Scale

#'

#' Map categorical values to colors.

#'

#' @param values Categorical values.

#' @param palette Color palette.

#' @return Character vector of colors.

#' @keywords internal

scale_color_discrete <- function(values, palette = "colorblind") {

  # Get colors

    } else {

    }

  } else {

  }

}

#' Create a Width Scale

#'

#' Map values to line widths.

#'

#' @param values Values to map.

#' @param range Output width range.

#' @return Scaled values.

#' @keywords internal

scale_width <- function(values, range = c(0.5, 3)) {

}

#' Create an Alpha Scale

#'

#' Map values to transparency.

#'

#' @param values Values to map.

#' @param range Output alpha range.

#' @return Scaled values.

#' @keywords internal

scale_alpha <- function(values, range = c(0.3, 1)) {

}

#' @title Group-based Layout

#' @description Arrange nodes in groups, with each group in a circular arrangement.

#' @name layout-groups

NULL

#' Group-based Layout

#'

#' Arrange nodes based on group membership. Groups are positioned in a

#' circular arrangement around the center, with nodes within each group

#' also arranged in a circle.

#'

#' @param network A CographNetwork object.

#' @param groups Vector specifying group membership for each node.

#'   Can be numeric, character, or factor.

#' @param group_positions Optional list or data frame with x, y coordinates

#'   for each group center.

#' @param inner_radius Radius of nodes within each group (default: 0.15).

#' @param outer_radius Radius for positioning group centers (default: 0.35).

#' @return Data frame with x, y coordinates.

#' @export

#'

#' @examples

#' # Create a network with groups

#' adj <- matrix(0, 9, 9)

#' adj[1, 2:3] <- 1; adj[2:3, 1] <- 1  # Group 1

#' adj[4, 5:6] <- 1; adj[5:6, 4] <- 1  # Group 2

#' adj[7, 8:9] <- 1; adj[8:9, 7] <- 1  # Group 3

#' net <- CographNetwork$new(adj)

#' groups <- c(1, 1, 1, 2, 2, 2, 3, 3, 3)

#' coords <- layout_groups(net, groups)

layout_groups <- function(network, groups, group_positions = NULL,

                          inner_radius = 0.15, outer_radius = 0.35) {

  }

  # Validate groups

  }

  # Convert to factor

  # Calculate group center positions

      # Single group: center

    } else {

      # Multiple groups: arrange in circle

      )

    }

  } else {

    } else {

    }

  }

  # Initialize coordinates

  # Position nodes within each group

    # Get nodes in this group

    # Group center

      # Single node: at center

    } else {

      # Multiple nodes: arrange in circle

    }

  }

}

#' @title Basic Node Shapes

#' @description Basic node shape drawing functions.

#' @name shapes-basic

#' @keywords internal

NULL

#' Draw Circle Node

#' @keywords internal

draw_circle <- function(x, y, size, fill, border_color, border_width,

                        alpha = 1, ...) {

  # Convert colors with alpha

    )

  )

}

#' Draw Square Node

#' @keywords internal

draw_square <- function(x, y, size, fill, border_color, border_width,

                        alpha = 1, ...) {

    )

  )

}

#' Draw Triangle Node

#' @keywords internal

draw_triangle <- function(x, y, size, fill, border_color, border_width,

                          alpha = 1, ...) {

  # Equilateral triangle points

    )

  )

}

#' Draw Diamond Node

#' @keywords internal

draw_diamond <- function(x, y, size, fill, border_color, border_width,

                         alpha = 1, ...) {

  # Diamond (rotated square)

    )

  )

}

#' Draw Pentagon Node

#' @keywords internal

draw_pentagon <- function(x, y, size, fill, border_color, border_width,

                          alpha = 1, ...) {

    )

  )

}

#' Draw Hexagon Node

#' @keywords internal

draw_hexagon <- function(x, y, size, fill, border_color, border_width,

                         alpha = 1, ...) {

    )

  )

}

#' @title Base R Edge Rendering

#' @description Edge drawing functions for splot() using base R graphics.

#' @name splot-edges

#' @keywords internal

NULL

#' Find Split Index for Curve Based on Arc Length Fraction

#'

#' Calculates the index at which to split a curve's coordinate arrays

#' so that the first segment covers a given fraction of the total arc length.

#'

#' @param x,y Vectors of curve coordinates.

#' @param fraction Desired fraction of total arc length (0-1).

#' @return Index at which to split the arrays.

#' @keywords internal

find_curve_split_index <- function(x, y, fraction) {

  # Calculate cumulative arc length

  # Find index where cumulative length crosses target

  # Ensure at least 2 points in each segment

}

#' Draw Curve with Optional Start Segment

#'

#' Draws a curve (as lines) with an optional differently-styled start segment.

#' Used internally to support dashed/dotted start segments for edge direction clarity.

#'

#' @param x,y Vectors of curve coordinates.

#' @param col Line color.

#' @param lwd Line width.

#' @param lty Main line type.

#' @param start_lty Line type for start segment.

#' @param start_fraction Fraction of curve for start segment (0-0.5).

#' @keywords internal

draw_curve_with_start_segment <- function(x, y, col, lwd, lty,

                                          start_lty = 1, start_fraction = 0) {

  # If no split needed, draw single line

  }

  # Find split index based on arc length

  # Draw start segment (dashed/dotted)

  }

  # Draw main segment (solid)

  }

}

#' Draw Straight Edge

#'

#' Renders a straight edge between two points with optional arrow.

#'

#' @param x1,y1 Start point coordinates.

#' @param x2,y2 End point coordinates.

#' @param col Edge color.

#' @param lwd Line width.

#' @param lty Line type.

#' @param arrow Logical: draw arrow at target?

#' @param asize Arrow size.

#' @param bidirectional Logical: draw arrow at source too?

#' @param start_lty Line type for start segment. 1=solid (default), 2=dashed, 3=dotted.

#' @param start_fraction Fraction of edge length for start segment (0-0.5). Default 0.

#' @param arrow_angle Arrow head angle in radians. Default pi/6 (30 degrees).

#' @keywords internal

draw_straight_edge_base <- function(x1, y1, x2, y2, col = "gray50", lwd = 1,

                                    lty = 1, arrow = TRUE, asize = 0.02,

                                    bidirectional = FALSE,

                                    start_lty = 1, start_fraction = 0,

                                    arrow_angle = pi/6) {

  # Calculate angle

  # qgraph-style: line ends at arrow base midpoint, arrow TIP at node boundary

    # Get arrow base midpoint (where line should end)

  } else {

  }

  # Shorten start if bidirectional

  } else {

  }

  # Draw line (ends at arrow base, not at tip)

  # If start_lty differs from main lty and start_fraction > 0, split into two segments

    # Calculate split point

    # Draw start segment (dashed/dotted)

    )

    # Draw main segment (solid)

    )

  } else {

    # Single line with uniform style

    )

  }

  # Draw arrow at target (TIP at node boundary)

  }

  # Draw arrow at source if bidirectional (TIP at node boundary)

  }

}

#' Draw Curved Edge with xspline (qgraph-style)

#'

#' Renders a curved edge using xspline() with optional arrow.

#' Uses qgraph-style curve calculation for smooth, natural-looking curves.

#' Curve direction is normalized so positive curve always bends the same

#' visual direction regardless of edge orientation.

#'

#' @param x1,y1 Start point coordinates.

#' @param x2,y2 End point coordinates.

#' @param curve Curvature amount (positive = clockwise, negative = counterclockwise

#'   when looking from source to target).

#' @param curvePivot Position along edge for control point (0-1).

#' @param col Edge color.

#' @param lwd Line width.

#' @param lty Line type.

#' @param arrow Logical: draw arrow at target?

#' @param asize Arrow size.

#' @param bidirectional Logical: draw arrow at source too?

#' @param start_lty Line type for start segment. 1=solid (default), 2=dashed, 3=dotted.

#' @param start_fraction Fraction of edge length for start segment (0-0.5). Default 0.

#' @param arrow_angle Arrow head angle in radians. Default pi/6 (30 degrees).

#' @keywords internal

draw_curved_edge_base <- function(x1, y1, x2, y2, curve = 0.2, curvePivot = 0.5,

                                  col = "gray50", lwd = 1, lty = 1,

                                  arrow = TRUE, asize = 0.02,

                                  bidirectional = FALSE,

                                  start_lty = 1, start_fraction = 0,

                                  arrow_angle = pi/6) {

    # Fall back to straight edge

  }

  # Edge vector and length

  # Defensive check for empty or NA values

  }

  # Perpendicular unit vector (rotated 90 degrees counter-clockwise)

  # Matches the (-dy, dx) convention used by the curve direction algorithm

  # Curve offset: proportional to edge length, with minimum so short edges still visibly curve

  }

  # Create smooth curve using multiple control points (qgraph approach)

  # Use 5 points for smoother curve: start, 1/4, mid, 3/4, end

    # Base point along edge

    # Parabolic offset - maximum at curvePivot, zero at ends

    # This creates a smooth symmetric curve

    # Adjust for pivot position (shift the peak)

      # Skewed parabola

      } else {

      }

    }

  }

  # Generate smooth xspline through control points

  # shape = 1 for smooth interpolation, 0 for corners at endpoints

  )

  # qgraph-style arrow positioning:

  # 1. Calculate arrow angle from curve direction

  # 2. Truncate curve to stop at arrow base

  # 3. Draw arrow with TIP at node boundary

    # 1. Calculate arrow angle from last curve segment

    # 2. Find arrow base midpoint (where curve should end)

    # 3. Truncate curve: remove points inside arrow radius

    # Keep only points outside the arrow (qgraph approach)

    # 4. Draw truncated curve + line to arrow base

    }

    # 5. Draw arrow with TIP at node boundary (x2, y2)

  } else {

    # No arrow - draw full curve

  }

  # Draw arrow at source if bidirectional

    # Calculate angle from curve start

    # Find arrow base midpoint at source

    # Truncate curve at source: remove points inside arrow radius

    # Keep only points outside the start arrow

    # Redraw if we need to truncate the start (overwrites previous line)

      # Clear and redraw with both ends truncated

      # If target also has arrow, truncate that end too

        }

      }

    }

    # Draw arrow at source

  }

}

#' Draw Self-Loop Edge (qgraph-style)

#'

#' Renders a self-loop (edge from node to itself) using a teardrop/circular

#' loop shape similar to qgraph.

#'

#' @param x,y Node center coordinates.

#' @param node_size Node radius.

#' @param col Loop color.

#' @param lwd Line width.

#' @param lty Line type.

#' @param rotation Angle in radians for loop direction (default: pi/2 = top).

#' @param arrow Logical: draw arrow?

#' @param asize Arrow size.

#' @param arrow_angle Arrow head angle in radians. Default pi/6 (30 degrees).

#' @keywords internal

draw_self_loop_base <- function(x, y, node_size, col = "gray50", lwd = 1,

                                lty = 1, rotation = pi/2, arrow = TRUE,

                                asize = 0.02, arrow_angle = pi/6) {

  # qgraph-style loop: circular arc outside the node

  # Loop size proportional to node size

  # Center of the loop arc (outside the node)

  # Generate circular arc (about 300 degrees, leaving gap for arrow)

  # Handle angle wrapping

  }

  # Draw the loop

  )

  # Draw arrow at end of loop

    # Arrow angle tangent to circle at endpoint

  }

}

#' Draw Edge Label

#'

#' Renders a label on an edge.

#'

#' @param x,y Label position coordinates.

#' @param label Text to display.

#' @param cex Character expansion factor.

#' @param col Text color.

#' @param bg Background color (or NA for none).

#' @param font Font face.

#' @param shadow Logical: enable drop shadow?

#' @param shadow_color Shadow color.

#' @param shadow_offset Shadow offset distance.

#' @param shadow_alpha Shadow transparency.

#' @keywords internal

draw_edge_label_base <- function(x, y, label, cex = 0.8, col = "gray30",

                                 bg = "white", font = 1,

                                 shadow = FALSE, shadow_color = "gray40",

                                 shadow_offset = 0.5, shadow_alpha = 0.5) {

  }

  # Draw background if specified

    # Estimate text size for background

    )

  }

  # Draw shadow text first (if enabled)

    # Convert points to user coordinate offset

    )

  }

  # Draw main text

  )

}

#' Get Label Position on Edge

#'

#' Calculates the position for an edge label (matches qgraph-style curves).

#' For curved edges, the label is offset perpendicular to the edge to avoid

#' overlapping with the edge line.

#'

#' @param x1,y1 Start point.

#' @param x2,y2 End point.

#' @param position Position along edge (0-1).

#' @param curve Curvature amount.

#' @param curvePivot Curve pivot position.

#' @param label_offset Additional perpendicular offset for the label (in user coords).

#'   Positive values offset in the same direction as the curve bulge.

#'   Default 0.03 provides good separation from the edge line.

#' @return List with x, y coordinates.

#' @keywords internal

get_edge_label_position <- function(x1, y1, x2, y2, position = 0.5,

                                    curve = 0, curvePivot = 0.5,

                                    label_offset = 0) {

  # Edge vector and length

  # Defensive check for empty or NA values

  }

  # Perpendicular unit vector (counterclockwise rotation)

    # Straight edge - position along line with perpendicular offset

    # Offset perpendicular to edge (default: above the line)

    ))

  }

  # Curved edge - match qgraph-style curve calculation

  # Same curve offset as draw_curved_edge_base

  }

  # Base point along edge

  # Parabolic offset for curve position

    } else {

    }

  }

  # Position on the curve

  # Add additional offset in the direction of the curve bulge

  # This moves the label to the convex side of the curve

  )

}

#' Render All Edges

#'

#' Renders all edges in the network.

#'

#' @param edges Edge data frame with from, to columns.

#' @param layout Matrix with x, y columns.

#' @param node_sizes Vector of node sizes.

#' @param shapes Vector of node shapes.

#' @param edge.color Vector of edge colors.

#' @param edge.width Vector of edge widths.

#' @param lty Vector of line types.

#' @param curve Vector of curvatures.

#' @param curvePivot Vector of curve pivot positions.

#' @param arrows Logical or vector: draw arrows?

#' @param asize Arrow size.

#' @param bidirectional Logical or vector: bidirectional arrows?

#' @param loopRotation Vector of loop rotation angles.

#' @param edge.labels Vector of edge labels or NULL.

#' @param edge.label.cex Label size.

#' @param edge.label.bg Label background color.

#' @param edge.label.position Label position along edge.

#' @keywords internal

render_edges_base <- function(edges, layout, node_sizes, shapes = "circle",

                              edge.color = "gray50", edge.width = 1, lty = 1,

                              curve = 0, curvePivot = 0.5, arrows = TRUE,

                              asize = 0.02, bidirectional = FALSE,

                              loopRotation = NULL, edge.labels = NULL,

                              edge.label.cex = 0.8, edge.label.bg = "white",

                              edge.label.position = 0.5) {

  # Calculate network center for inward curve direction

  # Vectorize parameters

  # Loop rotation

  } else {

  }

  # Get render order (weakest to strongest)

  # Storage for label positions

    # Self-loop